Employees of a small private company sort items to be distributed to victims of the crisis in eastern Ukraine at a collection point in Krasnoyarsk, July 3, 2014. The humanitarian aid is being collected in cooperation with the regional office of the Russian Red Cross.

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President Vladimir Putin told European Commission President Jose Manuel Barroso on Monday that Russia was coordinating with the Red Cross on sending humanitarian aid to Ukraine.

"It was noted that the Russian side, in collaboration with representatives of the International Committee of the Red Cross, is sending an aid convoy to Ukraine," the Kremlin said in a statement about the telephone conversation between the two leaders.

Meanwhile, Ukraine said the humanitarian mission will be led by Red Cross and has the "blessing" of US and Russia, according to the Associated Press.

Barroso cautioned Putin against military intervention in Ukraine, the EU said.

Also Monday, Ukrainian military spokesman Andriy Lysenko said Russia has massed 45,000 troops on the Ukraine border, backed by an array of heavy equipment including tanks, missile systems, warplanes and attack helicopters.

"As of 11 o'clock today, about 45,000 troops of the armed forces and internal forces of the Russian Federation are concentrated in border areas," Lysenko told a briefing.